RNF20 依赖性 H2B 泛素化对同源重组的调控。

Regulation of homologous recombination by RNF20-dependent H2B ubiquitination.

机构信息

Radiation Biology Center, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto 606-8501, Japan.

出版信息

Mol Cell. 2011 Mar 4;41(5):515-28. doi: 10.1016/j.molcel.2011.02.002.

DOI:10.1016/j.molcel.2011.02.002

Abstract

The E3 ubiquitin ligase RNF20 regulates chromatin structure by monoubiquitinating histone H2B in transcription. Here, we show that RNF20 is localized to double-stranded DNA breaks (DSBs) independently of H2AX and is required for the DSB-induced H2B ubiquitination. In addition, RNF20 is required for the methylation of H3K4 at DSBs and the recruitment of the chromatin-remodeling factor SNF2h. Depletion of RNF20, depletion of SNF2h, or expression of the H2B mutant lacking the ubiquitination site (K120R) compromises resection of DNA ends and recruitment of RAD51 and BRCA1. Consequently, cells lacking RNF20 or SNF2h and cells expressing H2B K120R exhibit pronounced defects in homologous recombination repair (HRR) and enhanced sensitivity to radiation. Finally, the function of RNF20 in HRR can be partially bypassed by forced chromatin relaxation. Thus, the RNF20-mediated H2B ubiquitination at DSBs plays a critical role in HRR through chromatin remodeling.

摘要

E3 泛素连接酶 RNF20 通过单泛素化组蛋白 H2B 来调节染色质结构，从而参与转录。在这里，我们发现 RNF20 可以独立于 H2AX 定位于双链 DNA 断裂（DSB）处，并且对于 DSB 诱导的 H2B 泛素化是必需的。此外，RNF20 对于 DSB 处 H3K4 的甲基化以及染色质重塑因子 SNF2h 的募集也是必需的。RNF20 的耗竭、SNF2h 的耗竭或表达缺乏泛素化位点（K120R）的 H2B 突变体，都会影响 DNA 末端的切除以及 RAD51 和 BRCA1 的募集。因此，缺乏 RNF20 或 SNF2h 的细胞以及表达 H2B K120R 的细胞，在同源重组修复（HRR）方面表现出明显的缺陷，并对辐射更加敏感。最后，通过强制染色质松弛，可以部分绕过 RNF20 在 HRR 中的功能。因此，RNF20 在 DSB 处介导的 H2B 泛素化在通过染色质重塑参与 HRR 中起着关键作用。